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NASA NTRSDate not supplied

Modeling Evolvable Water Recovery Systems for Short and Long-Duration Missions in Partial Gravity

Water recovery technologies on the International Space Station (ISS) are designed and optimized for microgravity environments, thus creating a need for innovative systems optimized for mission operations in the presence of gravity. Alternative water recovery technologies under research by the Life Support Systems division were compiled into a series of Partial Gravity Water Recovery System (PGWRS) architectures. Individual unit processes were modeled via fundamental physical-chemical process equations to simulate their method of treatment, including chemical or biological oxidation, flash evaporation, filtration, or adsorption and ion exchange. Dimension and sizing data were then utilized to scale each architecture. Modeling was completed on an assortment of architectures assuming three scenarios in which treatment methods could take advantage of partial gravity: a short-duration mission with a temporary surface habitat, a longer duration mission with a more permanent habitat, and a long duration mission with minimal resupply. Total system mass was estimated to quantitatively compare architectures within scenarios, but qualitative observations were also made regarding system robustness, flexibility, and capacity to meet more stringent demands. Technologies that traded most favorably between the scenarios were those that included a pre-oxidation stage to minimize mass loading to downstream absorption and ion exchange beds, exploited gravity in liquid-vapor separation processes, and reconstituted wastewater components into recyclable material streams.

Avery Carlson↗
NASA NTRS1998

Capillary-Driven Heat Transfer Experiment: Keeping It Cool in Space

Capillary-pumped loops (CPL's) are devices that are used to transport heat from one location to another--specifically to transfer heat away from something. In low-gravity applications, such as satellites (and possibly the International Space Station), CPL's are used to transfer heat from electrical devices to space radiators. This is accomplished by evaporating one liquid surface on the hot side of the CPL and condensing the vapor produced onto another liquid surface on the cold side. Capillary action, the phenomenon that causes paper towels to absorb spilled liquids, is used to "pump" the liquid back to the evaporating liquid surface (hot side) to complete the "loop." CPL's require no power to operate and can transfer heat over distances as large as 30 ft or more. Their reliance upon evaporation and condensation to transfer heat makes them much more economical in terms of weight than conventional heat transfer systems. Unfortunately, they have proven to be unreliable in space operations, and the explanation for this unreliability has been elusive. The Capillary-Driven Heat Transfer (CHT) experiment is investigating the fundamental fluid physics phenomena thought to be responsible for the failure of CPL's in low-gravity operations. If the failure mechanism can be identified, then appropriate design modifications can be developed to make capillary phase-change heat-transport devices a more viable option in space applications. CHT was conducted onboard the Space Shuttle Columbia during the first Microgravity Science Laboratory (MSL-1) mission, STS-94, which flew from July 1 to 17, 1997. The CHT glovebox investigation, which was conceived by Dr. Kevin Hallinan and Jeffrey Allen of the University of Dayton, focused on studying the dynamics associated with the heating and cooling at the evaporating meniscus within a capillary phase-change device in a low-gravity environment. The CHT experimental hardware was designed by a small team of engineers from Aerospace Design & Fabrication (ADF), the NASA Lewis Research Center, and the University of Dayton. The hardware consisted of two experiment modules that each contained an instrumented test loop (idealized capillary-pumped loop), a base unit for power conversion and backlighting, a display unit with 15 LED's (light-emitting diodes) to display temperatures, pressure, heater power, and time, a control unit to select heaters and heater settings, a cooling fan, and associated cables.

Lekan, Jack F.↗
NASA NTRS2002

Plant Production Systems for Microgravity: Critical Issues in Water, Air, and Solute Transport Through Unsaturated Porous Media

This NASA Technical Memorandum is a compilation of presentations and discussions in the form of minutes from a workshop entitled 'Plant Production Systems for Microgravity: Critical Issues in Water, Air, and Solute Transport Through Unsaturated Porous Media' held at NASA's Johnson Space Center, July 24-25, 2000. This workshop arose from the growing belief within NASA's Advanced Life Support Program that further advances and improvements in plant production systems for microgravity would benefit from additional knowledge of fundamental processes occurring in the root zone. The objective of the workshop was to bring together individuals who had expertise in various areas of fluid physics, soil physics, plant physiology, hardware development, and flight tests to identify, discuss, and prioritize critical issues of water and air flow through porous media in microgravity. Participants of the workshop included representatives from private companies involved in flight hardware development and scientists from universities and NASA Centers with expertise in plant flight tests, plant physiology, fluid physics, and soil physics.

Steinberg, Susan L.↗
NASA NTRS1990

Low-gravity fluid physics: A program overview

An overview is presented of the microgravity fluid physics program at Lewis Research Center. One of the main reasons for conducting low gravity research in fluid physics is to study phenomena such as surface tension, interfacial contact angles, and diffusion independent of such gravitationally induced effects as buoyant convection. Fluid physics is at the heart of many space-based technologies including power systems, thermal control systems, and life support systems. Fundamental understanding of fluid physics is a key ingredient to successful space systems design. In addition to describing ground-based and space-based low-gravity facilities, selected experiments are presented which highlight Lewis work in fluid physics. These experiments can be categorized into five theme areas which summarize the work being conducted at Lewis for OSSA: (1) isothermal/iso-solutal capillary phenomena; (2) capillary phenomena with thermal/solutal gradients; (3) thermal-solutal convection; (4) first- and second-order phase transitions in a static fluid; and (5) multiphase flow.

Source record↗
NASA NTRS2002

Constitutive Relation in Transitional Granular Flows

To study the constitutive behavior of granular materials, the presence of gravity is detrimental. Although empirical relations have been obtained for engineering designs to control granular flows on Earth, it is not known how well these Earthbound relations can be used in another gravity field. Fundamental understanding must be derived to reliably design for granular flows in space exploration. There are two extremes of granular flows of which significant amount of knowledge is available. One deals with a dense and quasi-static situation where the deformation rate nearly vanishes. The other deals with dilute and rapidly fluctuating grain velocities where particle inertia dominates. This project, funded by the NASA Microgravity Fluid Physics Program, aims to study this transitional regime via physical experiments and computer simulations. A conceptual model has been established as described below. There are two natural time scales in a granular flow. One is the travel time between two consecutive collisions and the other is the duration of a collision contact. At a very low shear-rate, the shear-induced particle velocity is low. Hence the travel time between collisions is longer than the contact time between colliding particles. Binary collisions prevail. As the shear-rate increases, the traveling time between collisions reduces and the probability of multiple collisions goes up. These particle groups disperse shortly after and new groups form. When shear-rate is further increased, clusters grow in size due to an increasing chance for free particles to join before groups have the time to disperse. The maximum cluster size may depend on the global concentration and material properties. As the solid concentration approaches zero, the cluster size goes to one particle diameter. The maximum possible cluster size under any condition is the container size, provided that the shear flow is inside a container. The critical shear-rates that dictate the initiation of the multiple contacts, and the size and lifetime of the collision clusters, are functions of the concentration also. A 'regime' theory has been proposed by Babic et al. This theory suggested that both the solid concentration, C, and the non-dimensional shear-rate, B, are important in determining the regimes of the granular constitutive law. Additional information is included in the original extended abstract.

Shen, Hayley H.↗
NASA NTRS1999

Constrained Vapor Bubble

The nonisothermal Constrained Vapor Bubble, CVB, is being studied to enhance the understanding of passive systems controlled by interfacial phenomena. The study is multifaceted: 1) it is a basic scientific study in interfacial phenomena, fluid physics and thermodynamics; 2) it is a basic study in thermal transport; and 3) it is a study of a heat exchanger. The research is synergistic in that CVB research requires a microgravity environment and the space program needs thermal control systems like the CVB. Ground based studies are being done as a precursor to flight experiment. The results demonstrate that experimental techniques for the direct measurement of the fundamental operating parameters (temperature, pressure, and interfacial curvature fields) have been developed. Fluid flow and change-of-phase heat transfer are a function of the temperature field and the vapor bubble shape, which can be measured using an Image Analyzing Interferometer. The CVB for a microgravity environment, has various thin film regions that are of both basic and applied interest. Generically, a CVB is formed by underfilling an evacuated enclosure with a liquid. Classification depends on shape and Bond number. The specific CVB discussed herein was formed in a fused silica cell with inside dimensions of 3x3x40 mm and, therefore, can be viewed as a large version of a micro heat pipe. Since the dimensions are relatively large for a passive system, most of the liquid flow occurs under a small capillary pressure difference. Therefore, we can classify the discussed system as a low capillary pressure system. The studies discussed herein were done in a 1-g environment (Bond Number = 3.6) to obtain experience to design a microgravity experiment for a future NASA flight where low capillary pressure systems should prove more useful. The flight experiment is tentatively scheduled for the year 2000. The SCR was passed on September 16, 1997. The RDR is tentatively scheduled for October, 1998.

Huang, J.↗
NASA NTRS2001

Absolute And Convective Instability and Splitting of a Liquid Jet at Microgravity

The objective is to establish a definitive role of the capillary, viscous, and inertial forces at a liquid-gas interface in the absence of gravity by using the fluid dynamics problem of the stability of a liquid jet as a vehicle. The objective is achieved by reexamining known theories and new theories that can be verified completely only in microgravity. The experiments performed in the microgravity facility at NASA Glenn Research Center enable the verification of the theory with experimental data. Of particular interest are (1) to capture for the first time the image of absolute instability, (2) to elucidate the fundamental difference in the physical mechanism of the drop and spray formation from a liquid jet, and (3) to find the origin of the newly discovered phenomenon of jet splitting on earth and in space.

Lin, S. P.↗
NASA NTRS2005

Fundamental Research Applied To Enable Hardware Performance in Microgravity

NASA sponsors microgravity research to generate knowledge in physical sciences. In some cases, that knowledge must be applied to enable future research. This article describes one such example. The Dust and Aerosol measurement Feasibility Test (DAFT) is a risk-mitigation experiment developed at the NASA Glenn Research Center by NASA and ZIN Technologies, Inc., in support of the Smoke Aerosol Measurement Experiment (SAME). SAME is an investigation that is being designed for operation in the Microgravity Science Glovebox aboard the International Space Station (ISS). The purpose of DAFT is to evaluate the performance of P-Trak (TSI Incorporated, Shoreview, MN)--a commercially available condensation nuclei counter and a key SAME diagnostic- -in long-duration microgravity because of concerns about its ability to operate properly in that environment. If its microgravity performance is proven, this device will advance the state of the art in particle measurement capabilities for space vehicles and facilities, such as aboard the ISS. The P-Trak, a hand-held instrument, can count individual particles as small as 20 nm in diameter in an aerosol stream. Particles are drawn into the device by a built-in suction pump. Upon entering the instrument, these particles pass through a saturator tube where they mix with an alcohol vapor (see the following figure). This mixture then flows through a cooled condenser tube where some of the alcohol condenses onto the sample particles, and the droplets grow in a controlled fashion until they are large enough to be counted. These larger droplets pass through an internal nozzle and past a focused laser beam, producing flashes of light that are sensed by a photodetector and then counted to determine particle number concentration. The operation of the instrument depends on the proper internal flow and recycling of isopropyl alcohol in both the vapor and liquid phases.

Sheredy, William A.↗
NASA NTRS2019

Deciphering the Effects of Microgravity Cell by Cell

Forces generated by gravity have a profound impact on the behavior of cells in tissues affecting the course of the cell cycle and differentiation fate of progenitors in mammalian tissues. These cells are contributing to normal tissue regenerative health and defence against disease. In Human space exploration context, it is extremely important to determine spaceflight provoked changes in tissue's regenerational capabilities. Microgravity experienced during spaceflight causes unloading and mechanical disuse on all orthostatic support tissues, therefore impacting stem cell fate and lineage commitment decisions. Investigating how ESCs respond to mechanical stimulation is a platform for fundamental developmental and regeneration research applicable for spaceflight. However, the gene expression programs associatiated with early committment stem cell pathways in response to physical stimulation are not readily known. Single-cell RNA-seq technologies have recently revolutionized the world of molecular biology by providing the capability to assess gene expression pattern within a single cell. Our method isolates and separately barcodes mRNAs from thousands of single cells and sequences their expressomes. Understanding regenerative processes on a molecular level would not only help reduce long-term spaceflight impact on health, but also may enable the development of novel tissue regenerative approaches to tissue degeneration on Earth.

Single cell sequencing↗
NASA NTRS1998

The Physics of Hard Spheres Experiment on MSL-1: Required Measurements and Instrument Performance

The Physics of HArd Spheres Experiment (PHaSE), one of NASA Lewis Research Center's first major light scattering experiments for microgravity research on complex fluids, flew on board the Space Shuttle's Microgravity Science Laboratory (MSL-1) in 1997. Using colloidal systems of various concentrations of micron-sized plastic spheres in a refractive index-matching fluid as test samples, illuminated by laser light during and after crystallization, investigations were conducted to measure the nucleation and growth rate of colloidal crystals as well as the structure, rheology, and dynamics of the equilibrium crystal. Together, these measurements support an enhanced understanding of the nature of the liquid-to-solid transition. Achievement of the science objectives required an accurate experimental determination of eight fundamental properties for the hard sphere colloidal samples. The instrument design met almost all of the original measurement requirements, but with compromise on the number of samples on which data were taken. The instrument performs 2-D Bragg and low angle scattering from 0.4 deg. to 60 deg., dynamic and single-channel static scattering from 10 deg. to 170 deg., rheology using fiber optics, and white light imaging of the sample. As a result, PHaSE provided a timely microgravity demonstration of critical light scattering measurement techniques and hardware concepts, while generating data already showing promise of interesting new scientific findings in the field of condensed matter physics.

Doherty, Michael P.↗
NASA NTRS1989

Microgravity combustion science: A program overview

The promise of microgravity combustion research is introduced by way of a brief survey of results, the available set of reduced gravity facilities, and plans for experimental capabilities in the Space Station era. The study of fundamental combustion processes in a microgravity environment is a relatively new scientific endeavor. A few simple, precursor experiments were conducted in the early 1970's. Today the advent of the U.S. space shuttle and the anticipation of the Space Station Freedom provide for scientists and engineers a special opportunity, in the form of long duration microgravity laboratories, and need, in the form of spacecraft fire safety and a variety of terrestrial applications, to pursue fresh insight into the basic physics of combustion. The microgravity environment enables a new range of experiments to be performed since buoyancy-induced flows are nearly eliminated, normally obscured forces and flows may be isolated, gravitational settling or sedimentation is nearly eliminated, and larger time or length scales in experiments become permissible. The range of experiments completed to date was not broad, but is growing. Unexpected phenomena have been observed often in microgravity combustion experiments, raising questions about the degree of accuracy and completion of our classical understanding and our ability to estimate spacecraft fire hazards. Because of the field's relative immaturity, instrumentation has been restricted primarily to high-speed photography. To better explain these findings, more sophisticated diagnostic instrumentation, similar to that evolving in terrestrial laboratories, is being developed for use on Space Station Freedom and, along the way, in existing microgravity facilities.

Source record↗
NASA NTRS1993

Overview of NASA's microgravity combustion science and fire safety program

The study of fundamental combustion processes in a microgravity environment is a relatively new scientific endeavor. A few simple, precursor experiments were conducted in the early 1970's. Today the advent of the U.S. space shuttle and the anticipation of the Space Station Freedom provide for scientists and engineers a special opportunity -- in the form of long duration microgravity laboratories -- and need -- in the form of spacecraft fire safety and a variety of terrestrial applications -- to pursue fresh insight into the basic physics of combustion. Through microgravity, a new range of experiments can be performed since: (1) Buoyancy-induced flows are nearly eliminated; (2) Normally obscured forces and flows may be isolated; (3) Gravitational settling or sedimentation is nearly eliminated; and (4) Larger time or length scales in experiments become permissible.

Ross, Howard D.↗
NASA NTRS1991

AIAA/IKI Microgravity Science Symposium, 1st, Moscow, USSR, May 13-17, 1991, Proceedings

The state of the art of microgravity science is examined in reviews and reports. Consideration is given to fluid physics; modeling and numerical analysis; crystal growth of electronic materials, proteins, metals, alloys, glasses, and ceramics; biotechnology, combustion science, microgravity hardware, and fundamental phenomena; and education. Particular attention is given to containerless science and technology, a low-gravity two-phase flow with heat transfer, numerical investigation on Benard instability in a finite liquid layer, synthesis and crystallization of refractory compounds from solutions in metallic melts under microgravitation conditions, the long duration protein crystallization experiment aboard the Mir Space Station, directional solidification in immiscible systems, formation of periodic layer structure in oxide melts under different gravity values, opposed flow flame spread in normal, enhanced, and reduced gravity, automatic equipment for semiconductor production in space, and consort and joust sounding rocket missions.

Source record↗
NASA NTRS1999

Initial Observations on the Burning of an Ethanol Droplet in Microgravity

Combustion of liquid ethanol represents an important system both from fundamental and practical points of view, Ethanol is currently being used as an additive to gasoline in order to reduce carbon monoxide and particulate emissions as well as to improve the fuel octane rating. A detailed physical understanding of liquid ethanol combustion is therefore necessary to achieve an optimal performance of such fuel blends in practical conditions. Ethanol is also a relatively simple model compound suitable for investigation of important combustion characteristics typical of more complex fuels. In particular, ethanol has been proposed for studies of sooting behavior during droplet burning. The sooting nature of ethanol has pressure sensitivities similar to that of n-heptane, but shifted to a higher range of pressures (1-3 atm). Additionally, liquid ethanol is miscible with water produced during its combustion forming mixtures with azeotropic behavior, a phenomenon important for understanding multi-component, liquid fuel combustion. In this work, we present initial results obtained in a series of recent space-based experiments and develop a detailed model describing the burning of ethanol droplet in microgravity.

Kazakov, Andrei↗
NASA NTRS2011

Issues of Long-Term Cryogenic Propellant Storage in Microgravity

Modern multi-layer insulation (MLI) allows to sharply reduce the heat leak into cryogenic propellant storage tanks through the tank surface and, as a consequence, significantly extend the storage duration. In this situation the MLI penetrations, such as support struts, feed lines, etc., become one of the most significant challenges of the tanks heat management. This problem is especially acute for liquid hydrogen (LH2) storage, since currently no efficient cryocoolers exist that operate at very low LH2 temperatures (20K). Even small heat leaks under microgravity conditions and over the period of many months give rise to a complex slowly-developing, large-scale spatiotemporal physical phenomena in a multi-phase liquid-vapor mixture. These phenomena are not well-understood nor can be easily controlled. They can be of a potentially hazardous nature for long-term on-orbital cryogenic torage, propellant loading, tank chilldown, engine restart, and other in-space cryogenic fluid management operations. To support the engineering design solutions that would mitigate these effects a detailed physics-based analysis of heat transfer, vapor bubble formation, growth, motion, coalescence and collapse is required in the presence of stirring jets of different configurations and passive cooling devices such as MLI, thermodynamic vent system, and vapor-cooled shield. To develop physics-based models and correlations reliable for microgravity conditions and long-time scales there is a need for new fundamental data to be collected from on-orbit cryogenic storage experiments. Our report discusses some of these physical phenomena and the design requirements and future studies necessary for their mitigation. Special attention is payed to the phenomena occurring near MLI penetrations.

Muratov, C. B.↗
NASA NTRS2002

Calcium/Calmodulin-Mediated Gravitropic Response in Plants

Plant organs respond to different physical signals such as gravity, light and touch. Gravity gives plants proper orientation, resulting in the proper form that we take for granted; the roots grow down into soil and shoots grow towards the light. Under microgravity conditions, as in space, plant growth patterns lack a clear sense of direction. Calcium and calmodulin (CaM) play an important role in gravity signal transduction. However, the molecular and biochemical mechanisms involved in gravity signal transduction are not clearly understood. The goal of this project was to gain a fundamental understanding of how calcium/calmodulin-mediated signaling is involved in gravity signal transduction in plants. During the grant period, significant progress was made in elucidating the role of calmodulin and its target proteins in gravitropism.

Poovaiah, B. W.↗
NASA NTRS1991

Microgravity Program strategic plan, 1991

The all encompassing objective of the NASA Microgravity Program is the use of space as a lab to conduct research and development. The on-orbit microgravity environment, with its substantially reduced buoyancy forces, hydrostatic pressures, and sedimentation, enables the conduction of scientific studies not possible on Earth. This environment allows processes to be isolated and controlled with an accuracy that cannot be obtained in the terrestrial environment. The Microgravity Science and Applications Div. has defined three major science categories in order to develop a program structure: fundamental science, including the study of the behavior of fluids, transport phenomena, condensed matter physics, and combustion science; materials science, including electronic and photonic materials, metals and alloys, and glasses and ceramics; and biotechnology, focusing on macromolecular crystal growth as well as cell and molecular science. Experiments in these areas seek to provide observations of complex phenomena and measurements of physical attributes with a precision that is enabled by the microgravity environment.

Source record↗
NASA NTRS2003

NASA Microgravity Combustion Science Research Plans for the ISS

A peer-reviewed research program in Microgravity Combustion Science has been chartered by the Physical Sciences Research Division of the NASA Office of Biological and Physical Research. The scope of these investigations address both fundamental combustion phenomena and applied combustion research topics of interest to NASA. From this pool of research, flight investigations are selected which benefit from access to a microgravity environment. Fundamental research provides insights to develop accurate simulations of complex combustion processes and allows developers to improve the efficiency of combustion devices, to reduce the production of harmful emissions, and to reduce the incidence of accidental uncontrolled combustion (fires, explosions). Through its spacecraft fire safety program, applied research is conducted to decrease risks to humans living and working in space. The Microgravity Combustion Science program implements a structured flight research process utilizing the International Space Station (ISS) and two of its premier facilities- the Combustion Integrated Rack of the Fluids and Combustion Facility and the Microgravity Science Glovebox - to conduct space-based research investigations. This paper reviews the current plans for Microgravity Combustion Science research on the International Space Station from 2003 through 2012.

Sutliff, Thomas J.↗